Slate is the longest lived common roof covering in Britain and the most demanding to lay. A natural slate roof laid properly outlives the people who commissioned it, and the price reflects skilled labour and a heavy material rather than anything complicated about the slate itself.
Natural, fibre cement and man made
Natural slate is quarried stone, in Britain most often Welsh or Cumbrian, and imported Spanish slate is the volume product on new work. It has a very long service life and considerable weight. Fibre cement slates are manufactured, much lighter, considerably cheaper, and have a shorter life, and they are the usual answer where the existing structure cannot take natural slate or the budget will not stretch. Man made composite slates sit between the two. They look similar from the pavement and they are not the same purchase.
How much does a slate roof cost, and why
Slating is a slow skilled trade. Each slate is holed and nailed individually to battens at a head lap calculated for the pitch and the exposure, valleys and hips are cut by hand, and there is far more labour per square metre than laying interlocking tiles. On a re roof the structure also matters: natural slate is heavy, so if the roof was built for something lighter the rafters and the wall plate need assessing. Add scaffolding, which a slate roof always needs, and the covering itself is a minority of the bill.
Slate roof repair cost UK-wide, and the nail sickness problem
Individual slipped slates are a straightforward repair, refixed with a copper or stainless tingle where the original nail has gone. What tells you more is how many are slipping. Nail sickness, where the fixings have corroded across the whole roof while the slates themselves are sound, is the classic end of life for a Victorian slate roof, and it presents as slates coming off steadily from everywhere. At that point patching is renting time: the roof is stripped, the sound slates are often salvaged and re laid with new battens, underlay and fixings.
What a local slate roofer's quote should name
The slate type and origin, its size and thickness, the head lap for your pitch, the fixing specification, whether battens and underlay are being renewed, what happens to the existing slates if they are being salvaged, how the valleys, hips and abutments are being detailed, and the access. On a period or listed building, ask what is being matched, because replacing Welsh slate with a different stone or with fibre cement changes the appearance of the elevation and may not be permitted.
Questions people ask about slate roof UK
How long does a slate roof last?
Natural slate has a very long service life, commonly outlasting the nails holding it. The usual end of a Victorian slate roof is nail sickness, where the fixings fail while the slates are still sound.
Can old slates be reused?
Frequently yes. Sound salvaged slates are re laid with new battens, underlay and fixings, which saves material and is common practice on period houses where matching matters.
Is fibre cement slate a reasonable substitute?
It is much lighter and cheaper with a shorter life, and it is the sensible answer where the structure cannot carry natural slate. On a listed building or in a conservation area it may not be acceptable.
Why is slating more expensive than tiling?
Labour. Each slate is holed and nailed individually and everything is cut by hand, so there is far more work per square metre than laying interlocking tiles.